When facing a fork in the road, neutrons appear to go one direction and their spins in the other

CURIOUS The Cheshire Cat in Alice in Wonderland can somehow separate its grin from the rest of its body. Similarly, a new experiment appears to detect neutron spins that are disconnected from the particles themselves.

Quantum mechanics has reached Alice in Wonderland levels of weirdness.

An experiment tracking subatomic particles maneuvering past a fork in the road seems to reveal that the particles went one way while one of their intrinsic properties, their spin, went in the other. Although the result conflicts with intuition, it agrees with a decade-old prediction. The phenomenon is called the quantum Cheshire Cat, after the Alice feline whose mischievous grin inexplicably remains after its body has disappeared.

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